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 TM 55-1905-219-14-7
3-205. HYDRAULIC CUB PUMP UNIT --MOTOR CONTROLLER - MAINTENANCE INSTRUCTIONS.
A.
GENERAL
1.
The motor controller is an A-C across-the-line non-reversing unit that controls the three-phase electric motor
used with the hydraulic pump on the steering system.
2.
The controller contains a LOCAL-OFF-REMOTE switch and a RESET control on the front panel and houses
a line contactor, power transformer, control relay, and fuses. The controller is used with a steering panel which provides
remote control of the motor starter. In such an installation, the control switch is normally in its REMOTE position. For
testing purposes, the switch can be turned to the LOCAL position, thereby energizing the contactor coil. In the OFF
position, the contactor control circuit is de-energized. The controller contains terminals to which the remote pump run
indicator lamp is connected to show when the motor is energized.
B.
DESCRIPTION.
1.
Starter contacts connect the motor directly to the power line upon actuation of the controller. Control circuits
are isolated from the power line by a 500-volt-ampere transformer that steps down the ship's supply to 115 volts. This
low voltage can also be used to energize indicator lamps and to supply 115 volts at 60 cps to the steering panel with
which the started may be used.
2.
A remote start switch (in a steering panel), or the LOCAL-OFF-REMOTE switch on the controller panel
closes a circuit through the coil of the main line contactor. The coil closes the three line contactors and connects the
motor to the power line as long as the switch remains closed. The main line contactor a1so closes the circuit to light a
"run" indicator lamp.
3.
If the motor load becomes excessive, either of three over-current thermal heaters in serieswith the motor
input opens the normally closed contacts in series with the coil of a control relay. This coil then releases its spring-loaded
contacts which close and energizes the overload circuit. The overload relay remains open until it is mechanically closed
by means of the RESET control. The motor remains connected to the power line despite the over-current because
continued operation is usually more important than possible damage to the motor and hydraulic steering equipment. For
this reason, an overload indicated should be investigated immediately and corrective action taken as soon as possible.
3-3190
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